Synthesis of substituted 7-octen-1-ols

ABSTRACT

Novel compounds, 7-octen-1-ols having one or two methyl groups in the 6 position are prepared by hydrolyzing an intermediate formed by reaction among aluminum, tetrahydropyran or an alkyl substituted tetrahydropyran, a hydrocarbyl aluminum hydride and butadiene or butadiene substituted on either or both of the internal carbon atoms. During at least a portion of the reaction period the reaction temperature must be in the range of from about 185* to about 210*C. so that there is formed an intermediate condensation product via cleavage of the ring of the tetrahydropyran reactant. The 7-octen-1-ols are useful as perfumes, monomers, chemical intermediates and surface active agents.

United States Patent [151 3,674,846

Brendel 1 *July 4, 1972 {54] SYNTHESIS OF SUBSTITUTED 7- 3,227,6401/1966 Foreman et al. ..260/638 B OCTEN-l-OLS OTHER PUBLICATIONS [72]Inventor: Gottfried J. Brendel, Baton Rouge, La.

[73] Assignee: Ethyl Corporation, New York, NY.

[ Notice: The portion of the term of this patent subsequent to Feb. 3,1987, has been disclaimed.

[22] Filed: Nov. 10, 1969 [21] Appl. No.2 875,554

[52] US. Cl. ..260/632 R, 252/89, 252/522,

252/DIG. 5, 252/DlG. 13, 252/D1G. 16, 260/448 R, 260/618 R, 260/633,260/966, 260/967 [51] Int. Cl. ..C07c 33/02, C1 1d 3/50 [58] Field ofSearch ..260/632 R, 631 R, 618 R [56] References Cited UNITED STATESPATENTS 3,493,623 2/1970 Brendel ..260/632 R 3,217,041 11/1965 Houlihan..260/631.5

3,244,752 4/1966 Eschinasi.... ..260/638 P Merck lndep, 6th ed., (1952),p. 253. Buendia, Chem Abstr., Vol. 66, (1967), p. 2714, item 28610 k.

Primary Examiner-Leon Zitver Assistant ExaminerJoseph E. EvansAttorney-Donald L. Johnson [57] ABSTRACT Novel compounds, 7-octen-l-olshaving one or two methyl groups in the 6 position are prepared byhydrolyzing an intermediate formed by reaction among aluminum,tetrahydropyran or an alkyl substituted tetrahydropyran, a hydrocarbylaluminum hydride and butadiene or butadiene substituted on either orboth of the internal carbon atoms. During at least a portion of thereaction period the reaction temperature must be in the range of fromabout 185 to about 210C. so that there is formed an intermediatecondensation product via cleavage of the ring of the tetrahydropyranreactant. The 7-octen-l-ols are useful as perfumes, monomers, chemicalintermediates and surface active agents.

16 Claims, No Drawings SYNTHESIS OF SUBSTITUTED 7-0CTEN-1-OLS Thisinvention relates to and has as its principal object the provision of7-octen-l-ols having one or two methyl groups in the 6 position and amethod for their synthesis.

The foregoing octcnols make up a hitherto unknown class of compounds. Asnear as can be determined a method for their synthesis has not beenavailable heretofore.

In accordance with this invention 7-octen-lols having one or two methylgroups in the 6 position are prepared by a twostep process. In the firststep, reaction is effected among aluminum, tetrahydropyran or an alkylsubstituted tetrahydropyran, a hydrocarbyl aluminum hydride, andbutadiene or butadiene substituted on either or both of its internalcarbon atoms by a hydrocarbyl group. For at least a portion of thereaction period the reaction mixture must be maintained at a temperaturefrom about 185 to about 210 C. In this way the tetrahydropyran or alkylsubstituted tetrahydropyran present in the reaction mixture is cleavedsuch that an aluminum-containing condensation product is produced.

In the second step of this process the foregoing intermediatecondensation product is subjected to hydrolysis. This hydrolysisreaction is readily effected by exposing the intermediate to the actionof water and more preferably to aqueous mineral acids or bases such ashydrochloric acid, sulfuric acid, aqueous sodium hydroxide solution, orthe like. The hydrolysis results in the liberation of the 7-octen-l-olshaving one or two methyl groups in the 6 position.

The optimum reaction conditions will of course vary to some extentdepending upon the characteristics of the particular reactants beingutilized. As noted above, the reaction mixture will be heated for atleast a part of the reaction period to a temperature in the range fromabout 185 to about 210 C. sufficient to form an intermediatecondensation reaction product through cleavage of the ring of thetetrahydropyran or alkyl substituted tetrahydropyran employed. ln mostcases it will be found desirable to heat the reactants for an initialperiod of time at a temperature in the range of from about 120 to about175 C. Thereafter the temperature is increased to between about 185 andabout 210 C. and held there for an additional period of time sufficientto result in the formation of the desired aluminum-containingcondensation product via cleavage of the six-membered ring of thetetrahydropyran reactant. The preferred cleavage temperatures for usewith tetrahydropyran and most lower alkyl substituted tetrahydropyransfall within the range of from about 190 to about 205 C. At thesetemperatures the cleavage reaction proceeds at a satisfactory rate andundesired side reactions are kept to a minimum.

The pressure within the reaction zone may be varied to suit the needs ofthe occasion. Ordinarily it will be found desirable to conduct thereaction at a superatmospheric pressure, for example, by conducting thereaction in a closed reactor under essentially autogenous pressure. Ingeneral, pressures ranging up to about 500 psig will be found suitableand convenient. Reaction times are likewise susceptible to variation andordinarily will range from a matter of a few minutes up to about 8 hoursor more. Generally speaking, the higher the reaction temperature theshorter the reaction time.

The aluminum used in the process of this invention may be in the form ofchips, turnings, powder, or other similar particulated states. It isdefinitely preferably to employ activated aluminum. Methods forproducing activated aluminum are standard and wall known in the art. Forfurther details, reference may be had, for--example, to 1.1.8. Pat. Nos.2,885,314; 2,892,738; 2,921,876; 3,100,786; and 3,104,252.

Cycloparaffinic monoethers used in the process of this invention arethose which contain one ether oxygen in a sixmember ring, the oxygenatom being\the only hereto atom present. In other words, in this processuse is made of tetrahydrophyran and alkyl substituted tetrahydropyrans,such as 2-methyltetra-hydropyi an; 2,2-dimethyl tetrahydropyran;2,2,6-trimethyl tetrahydropyran; 2,2,6,6- tetramethyl tetrahydropyran;2-pentyl tetrahydropyran; 2,6-

dimethyl tetrahydropyran; 2-propyl tetra hydropyran; 2,2,6-trimethyl-6-ethyl tetrahydropyran; Z-tridecyl tetrahydropyran; and thelike. On the basis of reactivity, availability, cost and usefulness ofend product, tetrahydropyran is the preferred monoether reactant.

The hydrocarbon aluminum hydride reactant used in the process may be adihydrocarbyl aluminum hydride (R AIH) in which the R groups arehydrocarbyl groups (alkyl, aryl, cycloalkyl, alkenyl, aralkyl, alkaryl,etc.).

Thus use may be made of such compounds as dimethylaluminum hydride,diethylaluminum hydride, dipropylaluminum hydride, dibutylalurninumhydride, diisobutylaluminum hydride, dioctylaluminum hydride hydrode,dioctadecylaluminum hydride, dicyclohexylaluminum hydride,dimethylcyclohexyl aluminum hydride, diallyallminum hydride,dibenzylaluminum hydride, diphenethylaluminum hydride and the like. Itis generally preferable to utilize a dialkylaluminum hydride,especially'those having alkyl groups containing up to about 18 carbonatoms. The most preferred compounds are the dialkylaluminum hydrides inwhich each alkyl group is a lower alkyl group and thus contains up toabout six carbon atoms. If desired, the hydrocarbon aluminum hydride maybe generated in situ by initially reacting aluminum with trihydrocarbylaluminum (e.g., triethylaluminum) under a hydrogen atmosphere accordingto known technology.

The diene reactant is a conjugated diene hydrocarbon e.g., butadiene orbutadiene substituted on either or both of the internal carbon atoms.This reactant will contain from four to about 18 carbon atoms in themolecule. Exemplary of such compounds are butadiene, isoprene,2,3-dimethyl butadiene, 2-ethyl butadiene, myrcene, 2-phenyl butadiene,and the like.

If desired, the foregoing reaction may be conducted in an ancillaryreaction diluent or solvent which is inert under the reaction conditionsbeing utilized. For example, use may be made of high boiling paraffinicor cycloparaffinic hydrocarbons which remain in the liquid state ofaggregation under the temperatures and pressures of the cleavagereaction. Ordinarily, however, the reaction will be carried out in theabsence of an ancillary solvent or diluent.

The relative proportions of the reactants do not appear to be criticalas long as there is present a sufficient amount of each reactant toparticipate in the reaction. It will of course be understood that thereaction mixture of the first step of the process should be keptessentially anhydrous and that excessive exposure of the system to airshould be avoided.

In the second step of the process of this invention thealuminum-containing intermediate reaction product is subjected tohydrolysis whereby the desired 6-methylated-7-octen-lol is liberated.Isolation and purification of the alkenol is achieved by conventionalmeans, e.g., distillation at reduced pressure, etc. The hydrolysis stepitself is normally performed at or below room temperature althoughtemperatures within the range of about --l0 to about 50 C. are usuallysatisfactory.

This invention and the various embodiments thereof may be furtherunderstood by reference to the following illustrative examples.

EXAMPLE I A mixture composed of 500 mmoles of isoprene, 15 grams ofactivated aluminum powder, 1.03 moles of tetrahydropyran and ofdiisobutylaluminum hydride was heated in a closed reaction vessel for 1hour at C. and then for 2 hours at C. After cooling to room temperature,a portion of the reaction product was hydrolyzed at 05 C. using dilutehydrochloric acid. This resulted in the liberation of 6,7-dirnethyl-7-octen-l-ol along with a lesser quantity of 6,6-dimethyl-7-octenJ-ol. These alkenols possess very desirable fragrancecharacteristics.

EXAMPLE II Repetition of the procedure of Example I using a reactiontemperature of 200 C. for 1.5 hours followed by hydrolysis results in ahigher yield of the same alkenols.

EXAMPLE Ill On heating 500 mmoles of butadiene, grams of activatedaluminum, one mole of tetrahydropyran, and 85 mmoles ofdiisobutylaluminum hydride in a sealed autoclave for 3 hours at 200 C.and then hydrolyzing the reaction mixture with water,6-methyl-7octen-1-ol is produced.

EXAMPLE lV By substituting 2,3-dimethyl butadiene-1,3 for the butadieneof Example Ill, the hydrolysis reaction results in the formation of6,6,7-trimethyl-7-octen-l-ol.

EXAMPLE V Example I is repeated using 2 -ethyl butadiene in place ofisoprene. Upon hydrolysis, a mixture of 6-methyl-7-ethyl-7- octen-l-oland 6-methyl-6-ethyl-7-octenl-ol is formed.

EXAMPLE VI A system composed of 500 mmoles of 2,3-dimethyl butadiene, l5grams of activated aluminum powder, one mole of 2-methyl tetrahydropyran and 85 mmoles of diisobutylaluminum hydride is sealed in anautoclave and heated for 1 hour at 150 C. and for 3 hours at 195 C. Roomtemperature hydrolysis of the resultant reaction product results in theformation of l ,6,6,7-tetramenthl-7-octen-l-ol.

Because of their fragrance characteristics many of the 6-methyl-7-octen-l-ols formed via the hydrolysis reaction are of utilityas perfumes, especially in connection with household detergents,shampoos, toilet bars and the like. Other utilities for these alkenolsinclude their use as monomers, intermediates for the synthesis ofpolyfunctional molecules (branched chain glycols, etc.) and as surfaceactive agents.

The 6-methylated-7-octen-l-ols may be halogenated or hydrohalogenatedand then used as, or converted into, plasticizers, flameproofing agents,pesticides, extreme pressure additives, and the like. For example,addition of bromine to the alkenols results in the formation of thecorresponding 6- methylated-7,S-dibromooctan-l-ols. These in turn may bereacted with PCI POCl or PSXl to produce dibromoalkyl phosphites,phosphates and thiophosphates.

Iclaim:

l. A compound selected from the group consisting of6-methyl-7-octen-l-ol,

6,7-dimethyl-7-octen-l-ol,

6,6-dimethyl-7-octen- 1 -ol,

6,6,7-trimethyl-7-octen- 1 -ol,

6-methyl-7-ethyl-7-octen- 1 -ol and 6-methyl-6-ethyl-7octen- 1 -ol.

2. A compound according to claim I, viz., 6-methyl-7- octen-l-ol.

3. A compound according to claim 1, viz., 6,7-dimethyl-7- octen-l-ol.

4. A compound according to claim 1, viz., 6,6-dimethyl-7- octen-l-ol.

5. A compound according to claim 1, viz., 6,6,7-trimethyl- 7-octen-1-ol.

6. A compound according to claim 1, viz., 6-methyl-7-ethyl- 7-octen- 1-ol.

7. A compound according to claim 1, viz., 6-methyl-6-ethyl- 7-octen- 1-ol.

8. A process of preparing a 7-octen-1-ol having one or two methyl groupsin the 6 position which comprises (a) reacting aluminum, acycloparafi'mic monoether selected from the group consisting oftetrahydropyran and alkyl substituted tetrahydropyrans, a hydrocarbylaluminum hydride, and a conjugated diene hydrocarbon selected from thegroup consisting of butadiene and butadiene substituted on either orboth of the internal carbon atoms and having up to 18 carbon atoms, atan elevated temperature in the range of from about to about 210 C.sufi'lcient to form an intermediate condensation reaction productthrough cleavage of the ring of said monoether, and (b) hydrolyzing thereaction product 9. The process of claim 8 wherem the reaction of (a) iseffected in a closed reactor and under essentially autogenous pressure.

10. The process of claim 8 wherein the aluminum is activated aluminum.

11. The process of claim 8 wherein the conjugated diene is butadiene,isoprene, 2,3-dimethyl butadiene-1,3, 2-ethyl butadiene or myrcene.

12. The process of claim 8 wherein said monoether is tetrahydropyran.

13. The process of claim 8 wherein the hydrocarbyl aluminum hydride is adialkylaluminum hydride.

14. The process of claim 8 wherein the hydrocarbyl aluminum hydride isdiisobutylaluminum hydride.

15. The process of claim 8 wherein the aluminum is particulate,activated aluminum; said monoether is tetrahydropyran; the hydrocarbylaluminum hydride is a dialkylaluminum hydride; and the conjugated dieneis butadiene, isoprene, 2,3- dimethyl butadiene-1,3, 2-ethyl butadieneor myrcene.

16. The process of claim 8 wherein the aluminum is particulate,activated aluminum; said monoether is tetrahydropyran; the hydrocarbylaluminum hydride is a dialkylaluminum hydride; the conjugated diene isbutadiene, isoprene, 2,3- dimethyl butadiene-1,3, 2-ethyl butadiene, ormyrcene; and the reaction of (a) is effected in a closed reactor at atemperature in the range of from about to about 205 C. under essentiallyautogenous pressure.

2. A compound according to claim 1, viz., 6-methyl-7-octen-1-ol.
 3. Acompound according to claim 1, viz., 6,7-dimethyl-7-octen-1-ol.
 4. Acompound according to claim 1, viz., 6,6-dimethyl-7-octen-1-ol.
 5. Acompound according to claim 1, viz., 6,6,7-trimethyl-7-octen-1-ol.
 6. Acompound according to claim 1, viz., 6-methyl-7-ethyl-7-octen-1-ol.
 7. Acompound according to claim 1, viz., 6-methyl-6-ethyl-7-octen-1-ol.
 8. Aprocess of preparing a 7-octen-1-ol having one or two methyl groups inthe 6 position which comprises (a) reacting aluminum, a cycloparaffinicmonoether selected from the group consisting of tetrahydropyran andalkyl substituted tetrahydropyrans, a hydrocarbyl aluminum hydride, anda conjugated diene hydrocarbon selected from the group consisting ofbutadiene and butadiene substituted on either or both of the internalcarbon atoms and having up to 18 carbon atoms, at an elevatedtemperature in the range of from about 185* to about 210* C. sufficientto form an intermediate condensation reaction product through cleavageof the ring of said monoether, and (b) hydrolyzing the reaction product.9. The process of claim 8 wherein the reaction of (a) is effected in aclosed reactor and under essentially autogenous pressure.
 10. Theprocess of claim 8 wherein the aluminum is activated aluminum.
 11. Theprocess of claim 8 wherein the conjugated diene is butadiene, isoprene,2,3-dimethyl butadiene-1,3, 2-ethyl butadiene or myrcene.
 12. Theprocess of claim 8 wherein said monoether is tetrahydropyran.
 13. Theprocess of claim 8 wherein the hydrocarbyl aluminum hydride is adialkylaluminum hydride.
 14. The process of claim 8 wherein thehydrocarbyl aluminum hydride is diisobutylaluminum hydride.
 15. Theprocess of claim 8 wherein the aluminum is particulate, activatedaluminum; said monoether is tetrahydropyran; the hydrocarbyl aluminumhydride is a dialkylaluminum hydride; and the conjugated diene isbutadiene, isoprene, 2,3-dimethyl butadiene-1,3, 2-ethyl butadiene ormyrcene.
 16. The process of claim 8 wherein the aluminum is particulate,activated aluminum; said monoether is tetrahydropyran; the hydrocarbylaluminum hydride is a dialkylaluminum hydride; the conjugated diene isbutadiene, isoprene, 2,3-dimethyl butadiene-1,3, 2-ethyl butadiene, ormyrcene; and the reaction of (a) is effected in a closed reactor at atemperature in the range of from about 190* to about 205* C. underessentially autogenous pressure.